I just got a 5 Qt KitchenAid at Sam's, 350 watt.
It stalls with heavy doughs, thats a no no for sure!
I am mixing doughs very moist from now on!
I got it so hot the moter was stinking! It still works fine.
Wish I had got the 525 watt one now but it might not do the 6 cup batches any better, live and learn.